Detector carriage



July 29, 1941.

w. c. BARNES EIAL 0, 60

DETECTOR CARRIAGE Filed June 6, 1938 7.1211 (4 77f075 alzer G. Ear/7,25

4. Sheets-Sheet l July 29,1941. w. c. BARNES ETAL DETECTOR: CARRIAGE 4 Sheets-Sheet 2 Filed June 6, 1938 y 29, 1941- w. c. BAR-MES ETAL 2,250,460

DETECTOR CARRIAGE Filed June 6, 1938 4 Sheets-Sheet s v Q g g ggijeyr 6.5621" 7 NNN QNN RNN July 29, 1941. w, c, BARN S ETAL 2,250,460

DETE ICTOR CARRIAGE Fi-ld June 6. 1938 4 Sheets-Sheet 4 with parts broken away Patented, July 29, 1941 ns'mc'roa cAnmAGE Walter Barnes, Lake Bluff, and Henry W.

Keevil, Highland Park, Ill.

Application June 6, 1938, Serial No. 212,122

19- Claims.

This invention relates to an improved detector carriage for use with rail flaw detecting apparatus; the principal objects of the invention being to provide a carriage which will more effectively follow the varying contours of rail than like carriages now known and used, and which is provided with means for facilitating the adjustment of the position of the pickup box with respect to therail.

Further and other objects and advantages will become apparent as the disclosure proceeds and the description is read in comunction with the accompanying drawings, in which Fig. 1 is a side elevational view showing the improved carriage mounted on the rear end of a detector car, a diagram being associated with the view showing the control means for raising and lowering the carriage;

Fig. 2 is a plan view of the improved carriage;

Fig. 3 is a fragmentary ing the manner in which mounted on the supporting arm;

Fig. 4 is a sectional view taken on the line 4-4 of Fig. 3; v

Fig. 5 is a plan view looking down on the carriage, with the upper portion of the carriage at the right of the figure broken away along the line 55 of Fig. 6;

Fig. 6 is a side elevational view of the carriage, to better illustrate the construction;

Fig. 7 is an end elevational view carriage mounting and assembly, view being from the left in Fig. 1;

Figs. 8, 9 and are vertical sectional views through the carriage, taken on the lines 8-'-8, 9-9 and |8-|8, respectively, of Fig. 6.

of the entire the point of General organization The detector carriage of this invention, generally designated 28, comprises an upper carriage 2|, and a lower carriage 22, the latter bein adapted to ride upon the rail 23 when the carriage is lowered without restraint from the upper carriage except for a lateral force transmitted to it by the upper carriage to hold it against the gauge edge of the rail, 'a slight downward force to hold it steady on the rail, and a longitudinal thrust for moving the lower carriage along the rail.

The upper carriage 2| is supported from the underframe 24 of the detector car by means of an arm 25, preferably of non-magnetic material,

' pivotally mounted on a shaft 26, trunnioned on a bottom plan view show-- the safety switch a horizontal plane about supporting bracket 21 fixed to the car underframe. The arm 25 is also pivoted about a vertical pin 28, so that the carriage can swing laterally with respect to the car body. The upper carriage 2| is secured. to the lower end of the arm 25 by a vertical pin 29 and a horizontal .pin 38, which permit the carriage as a whole to have longitudinal rocking and lateral swinging movement with respect to the arm.

Supporting mechanism for the detector carriage The entire supporting mechanism for the detector carriage is carried by the bracket 21, so that it can be easily and quickly installed on the car and removed when replacement or repairs are necessary. The bracket 21 is a relatively large casting having attaching flanges 3|, through' which bolts 32 pass for securing the bracket to the spaced side sills 33 at the side of the car. The

bracket has downwardly extending arms 35,

through which the shaft 26 extends, supported by suitable bearings, and adjustably positioned stop collars 35, on opposite sides of the arms 34, permit the shaft 26 to have limited sliding movement with respect to the bracket.

The arm 25 is mounted on the shaft 26 by means of a pivot block 36, which is clamped in the desired lateral position with respect to the shaft 26 and the rail beneath by a set-screw 31. The pivot bolt 28, which allows the arm 25 to have swinging movement in a more or less horizontal plane, screws into the block in a manner which is best shown in Fig. 4, with an enlarged shank 38 providing a bearing surface for the swin movement.

The lower end of the arm 25 has a horizontal portion 39 through which the vertical pivot pin 29 extends, as best shown in 9, and this pin also has an enlarged shank, asindicated at 40,

to provide the desired bearing surface for allowas a whole to swing in the pin. The pin 29 has its lower end screwed into a clevis 4|, through the jaw arms of which the horizontal pin or bolt 38 extends. The head of the pin 29 is bifurcated to receive a lift chain 42, associated with a lift cylinder, generally designated 43, and a pin 44 holds the chain in place.

The extreme rear end of the arm 25 supports a paint gun, generally designated 45, which is preferably mounted on the arm by a universal support which permits the angular position of the gun to be properly adjusted.

The upper end of the arm ing the detector carriage 25 (see Fig. 7) is resiliently connected to a fixed part of the car underframe lying inside of the plan projection of the track, by a spring 46, the connection being made by an adjustable screw 41 so that the tension of the spring 46 can be controlled. When the detector carriage is in operative position on the rail, the spring 46 is under tension, thereby applying a lateral force on the detector carriage to hold it in engagement with the gauge edge of the rail. When the carriage is raised from the rail, the spring is under light or no tension, since the entire carriage assembly is positioned inside of the gauge edge of the rail when in raised position, as will hereinafter appear.

The upper end of the arm 25 is also connected to the arms 34 of the bracket 21 by centering springs 48, the tension of which can be adjusted by means of adjusting screws 49. These screws are so placed and adjusted that when the carriage is in its raised position (as shown in dotted lines in Fig. 1), the springs 48 are under equal tension, with the result that they tend to align the arm 25 with the rail; but when the carriage is in operative position on the rail, the inside spring 48 is placed under greater tension due to the lateral shifting of the shaft 26, and the spring, therefore, acts with spring 45 in holding the carriage against the gauge edge of the rail.

The adjusting screw 41, to which the outer end of the spring 45 is attached, may be placed in any one of a number of openings 50 in the vertical angle 5| attached to the car underframe, so that the spring, in addition to exerting a lateral force on the arm (which causes it to swing about the pivot bolt 28) may also exert a varying vertical force, particularly a downwardly directed one on the carriage 20. Under ordinary circumstances, however, the weight of the arm itself, together withthe weight of the upper and lower carriages, is suflicient to cause the detector carriage to ride properly upon the rail.

Lift mechanism and associated controls In general it can be said that springs are used for holding the detector carriage in raised position when the car is running light, or passing over switches, frogs, and the like, and air pressure is used for lowering the carriage to testing position. Two air cylinders control the movement of the carriage, one of which is vertically positioned and serves to raise and lower the carriage, while the other is horizontally positioned and serves to control the lateral position of the carriage. The former, indicated by the reference character 43, is directly over the carriage and is supported at its upper end by trunnions on a bracket 52, attached to the car underframe. The piston 53 is normally held in raised position by a spring 54, but when air is admitted to the cylinder the piston is lowered to the position in which it is shown in Fig. 1, thereby allowing the carriage to move vertically into contact with the rail 23.

The carriage assembly, when in raised position, lies a slight distance inside of the gauge edge of the rail, and when the piston 53 is lowered by the introduction of air into the cylinder 43 the carriage moves in a vertical line until it strikes the rail (see the dotted lines in Fig. '7).

After the carriage has been seated on the rail the entire carriage assembly is shifted laterally by the action of the transverse cylinder, generally designated 55, which is pivotally mounted at one end by a pin 56 on an upstanding boss 51 on the supporting bracket 21, and has'its piston 58 connected by a push rod 59 to a vertical lever 60, fulcrumed at 6| on the supporting bracket 21, and having its lower end bifurcated to straddle the shaft 26 between closely spaced shaft collars 62. A spring 63 in the cylinder 55 normally holds the shaft 26 to the left (Fig. 7) as far as permitted by the stop collars 35, but when air is introduced into the cylinder 55 the piston 58 moves toward the center of the car and rocks the lever 60 to shift the shaft 26 to the right. This movement not only moves the entire carriage assembly toward the gauge edge of the rail, as

shown in Fig. 7, but it also tensions the spring 46, so that it also exerts a lateral pressure to maintain the detector carriage in constant engagement with the gaugeedge of the rail.

The air cylinders 43 and 55 are controlled by an electro-pneumatic system which is shown diagrammatically in Fig. 1. The system includes a compressor 64, connected to an air reservoir 65, through a check valve 66. A solenoid-operated master valve 51 controls the passage of air under pressure from the reservoir 65 to a solenoid-operated, detector carriage, valve 68, of which there is one for each of the carriages on opposite sides of the car. Whenever the valves 61 and 6B are positioned so that air from the reservoir is admitted to the pipe 69, the air immediately passes through the chamber '10 of the time delay device H and pipe 12 to the vertical cylinder 43 to lower the detector carriage.

' While this is taking place air slowly passes through a small groove 13 provided in the seat for the ball check valve 14 of the time delay device If, and after a predetermined time interval has elapsed (for example, three seconds) suflicient air pressure is built up in the horizontal cylinder 55 to move the piston 58 and cause the carriage assembly to be shifted into engagement with the gauge edge of the rail. The size of the groove I3 is such that the carriage is always lowered into contact with the rail before the transverse cylinder 55 operates, and in this way the carriage will always be properly seated on the rail, even though the car is standing on a curve when the carriage is lowered.

When the valve 68 is turned to a position such that the air in the pipe 69 is in communication with atmosphere, the air in the cylinders 43 and 55 is immediately exhausted from the cylinders, the ball valve 14 in the time delay device H moving back against the spring 15 to permit a quick release of the push-over cylinder 55.

The electrical circuit for controlling the pneumatic system consists of a generator 16, or other source of electro-motive force, connected across the solenoids 11 of the valves 68, and the solenoids 18 of the valve 61. Included in series with each solenoid 11 are the switch contacts of a time delay electrical relay, generally designated 80, the coil of which is energized from a battery {it whenever the seriesswitches 82 and 83 are both closed. The switch 82 is a manually controlled switch, while the switch 83 is an automatic switch carried on the arm 25 of the detector carriage assembly, and automatically opened whenever the arm 25 swings about the pivot 28 by an angular amount greater than normally results from the car rounding curves.

l Assuming that the master switch 84 has been closed, and that the detector. carriage shown in Fig. 1 is to be lowered to the rail, the switch 82 is actuated to close the circuit through the coil 80, which, after a predetermined time interval has, elapsed corresponding to the setting of the time delay element in the switch, closes the circuit 1 through the solenoid I1 and thereby causes air to be admitted to the pipe 88 to lower the carriage to the rail. When the switch 82 is opened the time delay relay, which is of the slow make, quick break type, immediately permits the relay contacts to drop away, thereby turning the valve 88 to the position in which it is shown in Fig. 1 to exhaust air from the pipe 88 to the atmosphere, whereupon the carriage is raised to inoperative position.

As will be seen from Fig. l, duplicate controls are provided for the detector carriage on the other side of the car, and it is obvious that the two carriages can be operated independently of one another.

The safety switch 83 consists of a contact arm 85, carried by the block 38 and extending rearwardly beneath a contact plate 88, mounted on the under side of the arm 25. The plate 88 is bounded on both sides by a flush insulating plate 81, so that when the arm 25 moves through an are that is greater than required for normal operation of the carriage, the circuit between the contact 85 and plate 88 is broken. This occurswhen the carriage is accidentally derailed by a switch point, frog, or the like. The critical angle for operation of the switch can be adjusted by laterally adjusting the contact plate assembly on the arm 25, for which adjustment pin and slot devices 88 are provided, and by adjusting the positlon of the contact 85 along the arm which extends rearwardly from the block 36, a slot 88 being provided in this arm for that purpose.

A centering spring 88 extending between the upper carriage 2I and the pivot block 38 steadies the carriage and alines it with respect to the rail when the carriage is lifted. It also relieves the front shoe II5 of excessive wear when the carriage is lowered.

If the carriage should by chance'miss the rail when being lowered, the excess vertical movement opens a switch adjustably mounted on the underframe 24, which functions in the same manner as the safety switch 83,111 lifting the carriage and automatically lowering'it again.

, The detector carriage, per se The function of the upper carriage 2I is to transmit vertical, lateral and longitudinal forces to the lower carriage so that the latter may properly ride on the rail 23. The downwardly directed forces, which may consist solely in the weight of the arm 25 and the upper carriage 2I, or the weight of these parts combined with the action of the spring 48 when secured to the bracket il in a manner to set up adownward force, are transmitted to the lower carriage by roller bearings, generally designated I88; the upwardly directed forces, consisting in forces used to raise the lower carriage from the rail, are transmitted through a self-centering lifting device, generally designated IN; the longitudinally directed forces transmitted 'from the upper carriage to the lower carriageare those which move the carriage along the rail, and these are transmitted through thrust lugs I82; and the laterally directed forces used for keeping the lower carriage in contact with the gauge edge of the rail are transmitted to the lower carriage through lateral pressure lugs, generally designated I83.

The upper carriage 2| comprises a yoke, preferably made of cast iron, having a horizontal portion I84 and downwardly extending legs I85,

The legs turn inwardly to form the thrust 11188 I82, these lugs having their upper surfaces V- shaped, as indicated at I88, tocooperate with the complementary undercut surfaces of the roller clips I81, which are secured to the end faces of the lower carriage 22 by bolts I88. Obviously when the arm 25 is raised by the lift cylinder 43 the combined thrust and'lift lugs I82 I engage the clip I81 and raise the lower carriage from the rail, centering it at the same time by the action of the complementary V-shaped surfaces.

The lower carriage 22 is also in the form of a yoke, and is preferably made of cast iron or other suitable material. It comprises legs I88, connected by an intermediate portion II8, from which the pickup unit III is adjustably supported. The legs I88 terminate in broad feet II2, each of which is provided with a vertical opening II3, to receive the lateral pressure lugs I83. These openings, are lined with hardened steel bushings II4 to resist wear. Manganese steel shoes I I5 are removably clamped to the feet by clips II6, held in place by bolts III. Preferably the shoes II5 are cast integrally with gauge runners II8, as best shown in Figs. 8 and 10, with reliefs formed at II8, I28, over the center of the rail and at the intersection of the gauge edge I2I of the rail with the top siu'face thereof,

respectively, to make the shoes ride with greater stability on the rail.

The combined .wear shoe and gauge runner are each provided with an opening I22, so that the pocket II3, which receives the lateral pressure lug I83, cannot become clogged with dirt and debris. The gauge runner is shaped to'provide maximum strength, and it is rounded at its ends to enable it to ride over obstacles.

The lateral pressure lugs I83 are threaded into the legs I85 of the upper carriage yoke, and each has an enlarged head I23 having sliding engagement with the liner II4 of the vertical opening I I3- The lateral forces transmitted fromthe arm 25 to the upper carriage 2I are evenly distributed between the lateral pressure lugs I83 at each end of the lower carriage 22 by the free swinging action of the carriage, resulting from its swivel connection through the pin 28 with the arm 25. Obviously there is comparatively little sliding movement between the lugs I83 and the liners II4, since the upper carriage normally rests on the lower carriage through the roller assemblies I88, with the result that the liners receive very little wear.

Each of the roller bearing assemblies I88, which transmits the downwardly directed forces from the upper carriage t9 the lower carriage; consists of a roller I24 mounted on a spacer bushing I25, which is clamped between the clip I81 and the recessed face I26 of the lower carriage by a bolt I21, threaded into the lower carriage, and acting as a pin to support the bushing I21 upon which the roller I24 rotates.

The upper carriage 2| is provided at each end with an enlargement I28, which is suitably machined to provide a bearing surface for the roller bearing I24, as best shown in Figs. 6 and 8.

In order to prevent the lower carriage from,

wardly from the upper carriage 2|, extend. The

stops limit the lateral angle-through which the lower car-riage can tilt with respect to the upper carriage.

It is obvious that both forward and rearward driving forces for the lower carriage are applied through the thrust lugs I 02.

The pickup box III, which houses the detector coil I3I, is provided with longitudinally extending flanges I32, which seat upon narrow shelves I33, adjustably supported from the intermediate portions III) of the lower carriage 22 by rods I34, the upper. portions of which extend through enlargements I35, and are provided with elongated faceted nuts I36, and the lower ends of which are provided with a rounded enlargement l3! which, with the shelves I33 and clamping plates I38, form a ball and socket Joint for supporting the pickup box from the rods. Springs I39 extend between the horizontal portion III! of the lower carriage yoke and the clamping plates I38 to keep the rods I34 in the lowest position permitted by the nuts I36, and incidentally serve as locking means for the nuts. Preferably the pickup box I I I is made of non-magnetic material.

The pickup box II I can be tilted laterally with respect to the longitudinal axis of the rail by loosening the elongated nuts I40, which clamp the plates I38 to the shelves I33, and then moving the box about the ball and socket joint until the desired position is reached, after which the nuts I40 are tightened to hold the box in adjusted position. The longitudinal tilting position of the box can be adjusted by obtaining the proper relative adjustment between the effective lengths of the two rods I34, and the lateral position of the box with respect to the rail can be adjusted by loosening nuts I4I which clamp the flanges I32 to the shelves of the pickup box, and then moving the box laterally to the desired position, after which the nuts I4I are again tightened. Transverse slots I42 are provided in the shelves I33 to permit this lateral adjustment to be made.

It has been found in practice that the detector carriage of this invention rides smoothly along the rail with the gauge runners H8 at all times in contact with the gauge edges of the rail. The detector carriage has a freedom of movement which enables it to follow all of the varying c'ontours of the'rail surface, and the entire carriage is capable of all adjustments which are necessary to insure proper riding qualities for the carriage and positioning of the pickup box with respect to the rail.

We claim as our invention- 1. In combination with a rail car, a detector carriage adapted to be supported on the car and moved along the rail surface, said carriage comprising an upper carriage suspended from the car, a lower carriage adapted to ride on the rail, and means including roller bearings for transmitting a downward force from the upper carriage to the lower carriage.

2. In combination with a rail car, a detector carriage adapted to be supported on the car and moved along the rail surface, said carriage comprising an upper carriage suspended from the car, a lower carriage adapted to ride on the rail, and means for transmitting a lateral force from the upper carriage to the lower carriage to urge the latter against the gauge side of the rail, said means including a lateral pressure lug carried by the upper carriage for engaging an upstanding surface on the lower carriage. V

3.-In combination with a rail car, a detector carriage adapted to be supported on the car and moved along the rail surface, said carriage comprising an uppercarriage suspended from the car, a lower carriage adapted to ride on the rail, and means for transmitting a lateral force from the upper carriage to the lower carriage to urge the latter against the gauge side of the rail, said means including a lateral pressure lug extending into a vertically disposed opening in the lower carriage.

4. In combination with a rail car, a detector carriage adapted to be suspended on the car and moved along the rail surface, said carriage comprising upper and lower carriage portions, the former being in the form of a yoke which straddles the latter with the legs of the yoke extending longitudinall of the carriage, and lateral pressure lugs carried by the yoke legs having sliding engagement with upstanding surfaces on the lower carriage.

5. In combination with a rail car, a detector carriage adapted to be suspended on the car and moved along the rail surface, said carriage comprising an upper carriage and a lower carriage, and means for transmitting a downward and lateral force from the upper carriage to the lower carriage, said means including a roller bearing for transmitting the downward component of the force to the lower carriage and a stop for limiting the lateral angular relationship between the upper and lower carriages.

6. In combination with a rail car, a detector carriage adapted to be suspended on the car and moved along the rail surface, said carriage comprising an upper carriage and a lower carriage, and means proximate the rail for transmitting a lateral force from the upper carriage to the lower carriage, and a stop operative between the upper carriage and the top portion of the lower carriage for limiting the lateral angular relationship between the upper and lower carriages.

7. In combination with a rail car, a carriage adapted to be supported on the car and moved along the rail surface, said carriage comprising an upper carriage and a lower carriage, means for transmitting a lateral force from the upper carriage to the lower carriage, said means including a stop for limiting the lateral angular relationship between the upper and lower carriages, said stop comprising a vertical lug carried by the upper carriage and extending between spaced side walls on the lower carriage.

8. In combination with a rail car, a carriage adapted to be supported on the car and moved along the rail surface, said carriage including an integrally formed wear shoe and gauge runner along one side only thereof having reliefs over the center of the rail and at the intersection of the gauge edge of the rail with the top surface of the rail.

9. In combination with a rail car, a carriage adapted to be supported on the car and moved along the rail surface, said carriage comprising an upper carriage and a lower carriage, and means for transmitting downward, lateral and longitudinal forces from the upper carriage to the lower carriage, said means including a roller bearing on the lower carriage in working contact with the upper carriage, a lug on the upper carriage engaging an upstanding surface on the lower carriage for transmitting longitudinal forces, and a lateral pressure lug carried by said lug and having a sliding bearing contact with an upstanding surface on the lower carriage.

10. In combination with a rail car, a carriage adapted to be supported on the car and moved along the rail surface, said carriage including an upper carriage and a lower carriage, and means for transmitting vertical forces between the upper carriage and the lower carriage. said means including a horizontal bearing pin on the lower carriage, a roller mounted on said pin and in bearing contact with the upper carriage under normal operating conditions, and a lifting lug on the upper carriage engaging an undercut surface on the lower carriage when the upper carriage is moved upwardly.

11. In combination with a rail car, a carriage adapted to be supported on the car and moved along the rail surface, said carriage including a yoke having downwardly extending legs and an intermediate raised portion, and means for adjustably supporting a pickup box from said raised portion, said means including a vertically adjustable rod at each end of the box secured to said intermediate portion of the yoke, a ball and socket joint between the lower ends of said rods and the ends of the pickup box, and means for clamping the ball and socket joint in adjusted position.

12. In combination with a rail car, a carriage adapted to be supported on the car and moved along the rail surface, said carriage including a yoke having downwardly extending le s and an intermediate raised portion, means for adlustably supporting a pickup box from said raised portion. said means including a vertically adjustable rod at each end of the box secured to said intermediate portion of the yoke, a ball and socket joint between the lower ends of said rods and the ends of the pickup box, means for clamping the ball and socket joint in adjusted position, and means for shifting the pickup box laterally with respect to the rods.

13. In combination with a rail car, a carriage adapted to be supported on the car and moved along the rail surface, said carriage comprising an upper carriage supported from the car by a vertically pivoted arm, means for applying a yielding lateral force to the upper carriage through said arm, a lower carriage adapted to be raised and lowered from the rail by the upper carriage but which when in operative position on the rail rides along the upper and gauge surfaces of the rail without restraint other than the lateral force transmitted to it by the upper carriage, and a longitudinal force exerted by the upper carriage for moving the lower carriage along the rail, and means for transmitting said lateral and longitudinal forces from the upper carriage to the lower carriage, said means including longitudinally spaced lateral pressure lugs on the upper carriage engaging upstandin surfaces on the lower carriage, a vertical pivotal connection between the upper carriage and the arm, and a thrust lug on the upper carriage engaging an upstanding surface on the lower carriage for moving the lower carriage along the rail.

14. In combination with a rail car, a carriage adapted to be supported on the car and moved along the rail surface, said carriage including an upper carriage and a lower carriage. and means for transmitting vertical forces between the mitting downward forces upper and lower carriages including a horizontal pin on the lower carriage having one end supported by a clip having an undercut V-shaped surface, a roller mounted on the pin for transfrom the upper carriage to the lower carriage, and a lift lug carried by' the upper carriage adapted to engage the V-shaped surface of the clip for raising the lower carriage from the rail.

15, In apparatus for car, a detector carriage mounted on the car, means for raising and lowering the carriage, automatic means for lifting the carriage whenever the carriage moves downwardly beyond a predetermined point, and means for automatically lowering the carriage after it has again alined itself with the rail.

16. In combination with a rail car, a detector carriage comprising an upper carriage whose weight is supported from the car, a lower carriage adapted to ride on the rail, roller means between the upper and lower carriages for transmitting a downward force from the upper carriage to the lower carriage to hold the latter downwardly against the rail, a post on one of the carriages, a well upon the other carriage receiving the post, said post and well being so constructed and arranged as to convey a force between the carriages transverse to the rail.

1'1. In combination with a rail car, a detector carriage suspended from the car at one side thereof comprising upper and lower portions movable laterally with respect to each other. means for limiting relative movement between said portions at vertically spaced points, means for moving the carriage downwardly and outwardly towards the gauge side of the rail, rolling means for transmitting the downward pressure between the portions, and guide means for locating the lower portion with respect to the gauge side of the rail.

18. In combination with a rail,car, a carriage adapted to be supported on the car and moved along the rail surface, said carriage including an integrally formed'wear shoe and gauge runner along one side only thereof and having a relief at the intersection of the gauge edge of the rail with the top surface of the rail.

19. In combination with a rail car, flaw detector mechanism including a carriage adapted to be supported on the car and moved along the rail surface. said device comprising an upper and a lower carriage, one of said carriages having a substantially horizontal concave face providing a track, av roller on the other of said carriages engaging said, rack, said track and roller transmitting a vertical force between said carriages, means supporting one carriage with respect to the other and providing lateral movement of one carriage with respect to the other, stop means for limiting said lateral movement including a vertical lug upon one of the carriages extending between spaced side walls on the other of said carriages.

WALTER C. BARNES. HENRY-W. KEEVIL.

detecting flaws in was, a

' Patent n 2,25d,l .6 0.

CERTIFICATE or CORRECTION. July 29,'191 1. WALTER c. BARNES, ET AL,

It is hereby certified that error appears in the printed specification of the above numbered "patent requiring correction as follows: Page 1;, sedond column, lines and7l, claim 9, for the word "lug" rea i --legand that the said Letters Patent should be read with thi s correction therein that the same may conform to therecord of the case in the Patent Office.

Signed and sealed this 9th day of September, A. 1 191 1.

Henry Van Arsdale, (Seal) Acting Commie sionerpf Patents 

